In the drafting art certain symbols and geometric figures of various sizes are repetitively required on a drawing. To avoid the time consuming procedure of drawing such figures, employing conventional instruments, such as triangles, compass, protractor, etc., it has long been the practice to provide templates with apertures therein, the edges of which are so shaped to form the desired figure by moving a pencil or pen around opening guide edges. Thus, templates having various size circles, ellipses, squares, hexagons, etc. are familiar. Due to the non-adjustability of such templates, however, they are limited somewhat in utility in that only one predetermined figure may be drawn with each aperture, or, if only a portion of the aperture is employed, then conventional drafting instruments must also be employed. Thus, if a slot with semi-circular ends is desired, one half of a circular aperture may be employed for each end and the figure completed by connecting such ends, employing a straight edge of any suitable form. This saves little time over the use of compass and T-square, or the like, and suffers the further disadvantage that skill is always required to join lines in exact alignment in contradistinction to a template wherein the line is continuous, the only points of alignment being at its starting and finishing point, which with a template, are usually overlapped.
Adjustable templates have also been proposed so that a predetermined size and shape of figure may be selected. The U.S. Patent to Lane No. 2,720,706 is exemplary of such type of template in which figures of several shapes having straight sides may be drawn. Until such time that an adjustable template is devised with which any shape and any size figure may be drawn, templates of this type will have their limitations in utility. Such limitations are not objectionable, however, if a specific template serves the major purposes of a draftman for a particular type of drawing. Moreover, in view of the relatively low cost of simple limited utility templates, as compared to a yet undevised and necessarily complicated adjustable all purpose template, the use of several limited utility templates will probably always be more economically practical.